Stable dispersions of polyaddition products of diisocyanates and bifunctional primary or secondary amines, hydrazines or hydrazides in polypropylene glycol ethers are generally known. Dispersions of this type may be prepared by initially introducing the amine component in solution in the polyether and adding the diisocyanate dropwise at room temperature (see, e.g. German Auslegeschrift No. 1,260,142). However, even very small quantities of the polyaddition product (from 2 to 5%) are sufficient to produce a considerable increase in viscosity.
Polyurethane foams with improved mechanical properties (more especially increased tensile strength and hardness) may be produced from dispersions of the type in question by reaction with polyisocyanates. However, dispersions with a resinous solids content of approximately 10% by weight have to be used in order to obtain distinct improvements in the property spectrum which comply with the requirements of the motor vehicle and upholstery industries. Unfortunately, dispersions with a solids content as high as this, produced by the process described in German Auslegeschrift No. 1,260,142 (U.S. Pat. No. 3,325,421), may only be commercially processed into polyurethane foams in low-pressure machines on account of their high viscosity. However, most foam manufacturers use high-pressure machines in which the starting materials must have viscosities of less than 2500 cP at 25.degree. C. The dispersions produced in accordance with German Auslegeschrift No. 1,260,142 are not suitable for foaming in high-pressure machines because of their high viscosities. Thus, for example, the reaction of tolylene diisocyanate with hydrazine in a standard commercial-grade soft foam polyether to form a 10% dispersion in accordance with German Auslegeschrift No. 1,260,142 gives a product with a viscosity of more than 10,000 cP/25.degree. C.
Accordingly, an object of the present invention is to provide non-sedimenting dispersions of polyureas and polyhydrazo-dicarbonamides or corresponding mixed polyaddition products in hydroxyl group-containing organic materials with viscosities of less than 2500 cP/25.degree. C at a resinous solids content of approximately 10% by weight.